Corrosion inhibition

ABSTRACT

The present invention provides a composition in contact with a corrodable metal surface, comprising a functional fluid and, as corrosion inhibitor, a compound having the formula I: ##STR1## as well as salts or esters thereof, wherein R 1  is C 4  -C 20  linear or branched alkyl, phenyl or C 7  -C 20  alkylphenyl; 
     R 2  is C 1  -C 12  linear or branched alkyl, phenyl or C 7  -C 20  alkylphenyl, or arylalkyl containing 7-20 carbon atoms; 
     X is CH 2 , O or S; 
     Y is O or S; and 
     Z is --(CH 2 ) n  -- in which n is 1, 2, 3, 4 or 5, or Z is --CH 2  --CH(CH 3 )--. 
     Some of the compounds of formula I are new.

The present invention relates to corrosion inhibition and, inparticular, to ether acid compounds which are active as corrosioninhibitors in functional fluids.

Many compounds or formulations are known to inhibit the corrosion offerrous metals in contact with aqueous or partially aqueous systems.Traditionally, such corrosion inhibitors contain metals such as chromiumor zinc, phosphorus in the form of phosphate, polyphosphate orphosphonate, or sodium nitrite. Most of these known corrosion inhibitorsare now believed to have an adverse effect on the environment when theyare discharged into waterways e.g. rivers, lakes. The known corrosioninhibitors can cause environmental damage due to their toxicity or totheir tendency to promote biological growth.

Many carboxylic acid derivatives have been examined as alternativecorrosion inhibitors. Generally however, high additive levels arerequired if carboxylic acid derivatives are to provide acceptablecorrosion-inhibiting performance.

Polymeric carboxylic acids have also been described as corrosioninhibitors but again, high levels of additive are normally required.

According to the present invention, there is provided a composition incontact with a corrodable metal, preferably a ferrous metal surface,comprising a functional fluid and, as corrosion inhibitor, a compoundhaving the formula I: ##STR2## as well as salts or esters thereof,wherein R¹ is C₄ -C₂₀ linear or branched alkyl, phenyl or C₇ -C₂₀alkylphenyl;

R² is C₁ -C₁₂ linear or branched alkyl, phenyl or C₇ -C₂₀ alkylphenyl,or arylalkyl containing 7-20 carbon atoms;

X is CH₂, O or S;

Y is O or S; and

Z is --(CH₂)_(n) -- in which n is 1, 2, 3, 4 or 5, or Z is --CH₂--CH(CH₃)--.

By the term "esters" of a compound of formula I, we mean that the CO₂ Hgroup in the compound of formula I is esterified to a group of formula--CO₂ M in which M is C₁ -C₄ alkyl optionally interrupted by one O-atom,C₇ -C₉ phenylalkyl, C₇ -C₁₈ alkylphenyl or C₆ -C₁₀ aryl.

Salts of compounds of formula I are preferably metal-, ammonium-, oramine salts, especially salts of alkali metals, alkaline earth metals,metals of groups IIB, IIIA or VIII of the Periodic System of Elements,ammonium salts or salts of organic amines. Specific examples are sodium,potassium, calcium, magnesium, aluminium, ammonium, tri(C₁ -C₄)alkylammonium, bis- and tris(hydroxyethyl)ammonium, octylamine anddodecylamine salts.

When R¹ is C₄ -C₂₀ linear or branched alkyl it may be, e.g. n-butyl,sec.-butyl, tert.-butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl,n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl,n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl,n-nonadecyl or n-eicosyl.

R¹ or R² as C₇ -C₂₀ alkylphenyl may be e.g. o-, m- or p-tolyl,-ethylphenyl, -n-propylphenyl, -n-butylphenyl, -t-butylphenyl,-n-pentylphenyl, -n-hexylphenyl, -n-heptylphenyl, tert-octylphenyl,nonylphenyl or dodecylphenyl.

R² as C₁ -C₁₂ linear or branched alkyl may be e.g. methyl, ethyl,n-propyl, isopropyl, n-butyl, sec.-butyl, tert.-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl orn-dodecyl.

R² as C₇ -C₂₀ arylalkyl may be e.g. 1- or 2-phenylethyl, 2- or3-phenylpropyl, or, preferably, benzyl.

Some of the compounds of formula I are known, but not for use ascorrosion inhibitors in functional fluids.

For example, in GB No. 1592600, there are described, as textileconditioning agents, compounds having the formula: ##STR3## whereinR^(a) and R^(b) are C₄ -C₈ alkyl;

Z^(a) is, inter alia, --(CH₂)_(x) CO₂ M¹ in which x is 1, 2 or 3 and M¹is e.g. alkali metal; and y is 0, 1, 2, 3 or 4.

In EP No. 23,333 textile soft rinsing agents are disclosed containingcompounds having the formula: ##STR4## wherein R^(c) is inter alia C₄-C₂₀ alkyl or optionally alkyl-substituted aryl;

Xa and Ya are hydrogen or methyl but may not be simultaneously methyl;na is O or an integer from 1 to 20; and

Z^(b) is e.g. --(CH₂)_(m) CO₂ M in which m is 0, 1, 2 or 3 and M is e.g.an alkali metal ion.

EP No. 144990 describes, inter alia, as silver halide solvents,thioether compounds having the formula: ##STR5## wherein R^(d) andR^(e), independently, are, inter alia C₁ -C₅ alkyl.

Accordingly, the present invention provides new compounds having theformula IA: ##STR6## as well as salts or esters thereof, wherein R³ isC₉ -C₂₀ linear or branched alkyl, phenyl or C₇ -C₂₀ alkylphenyl;

R⁴ is C₁ -C₃ alkyl;

and Z, X and Y have their previous significance.

Preferred compounds of formula I or IA are those wherein:

R¹ or R³ is C₉ -C₁₆ linear or branched alkyl, phenyl or C₇ -C₁₅alkylphenyl;

R² or R⁴ is C₁ -C₃ linear or branched alkyl;

X is CH₂, O or S;

Y is O; and

Z is --(CH₂)_(n) -- in which n is 1 or 2.

Specific examples of new compounds of formula IA include:

2-(1-Methoxymethylundecyloxy)acetic acid

2-(1-Methoxymethyltridecyloxy)acetic acid

2-(1-Methoxymethylpentadecyloxy)acetic acid

3-(1-Methoxymethylundecyloxy)propanoic acid

3-(1-Methoxymethyltridecyloxy)propanoic acid

3-(1-Methoxymethylpentadecyloxy)propanoic acid

2-Carboxymethyl-1-decyl-3-methylglycerol

2-Carboxymethyl-1-dodecyl-3-methylglycerol

2-Carboxymethyl-1-tridecyl-3-methylglycerol

2-Carboxymethyl-1-tetradecyl-3-methylglycerol

2-Carboxymethyl-1-hexadecyl-3-methylglycerol

2-Carboxymethyl-1-(4-nonylphenyl)-3-methylglycerol

2-Carboxymethyl-1-(4-dodecylphenyl)-3-methylglycerol

2-(2-carboxyethyl)-1-decyl-3-methyl glycerol

2-(2-carboxyethyl)-1-dodecyl-3-methyl glycerol

2-(2-carboxyethyl)-1-tridecyl-3-methyl glycerol

2-(2-carboxyethyl)-1-tetradecyl-3-methyl glycerol

2-(2-carboxyethyl)-1-hexadecyl-3-methyl glycerol

2-(2-carboxyethyl)-1-(4-nonylphenyl)-3-methyl glycerol

2-(2-carboxyethyl)-1-(4-dodecylphenyl)-3-methyl glycerol

2-Carboxymethyl-1-methyl-3-octylthio glycerol

2-Carboxymethyl-1-methyl-3-dodecylthio glycerol

2-Carboxymethyl-1-methyl-3-hexadecylthio glycerol.

For completely aqueous systems, preferred compounds of formula I or IAare those wherein R¹ or R³ is C₉ -C₁₆ linear alkyl, R² is C₁ -C₃ linearalkyl X is CH₂ or O, Y is O, Z is --(CH₂)_(n) -- in which n is 1 or 2.

The compounds of formula I or IA may be prepared by, in a first step,reacting a compound having the formula II: ##STR7## wherein R¹ or R³ andX have their previous significance, in the presence of a catalyst, witha compound of formula III:

    R.sup.2 --Y--H or R.sup.4 --Y--H                           III

wherein R² has its previous significance, to produce a compound offormula IV: ##STR8## wherein R¹, R², R³, R⁴, X and Y have their previoussignificance.

The reaction is conveniently performed using an excess of reagent IIIunder alkaline conditions. The catalyst may be an amine or anion-exchange resin, but is preferably sodium metal.

The compound of formula IV is then treated with a compound V capable ofconverting the CH(OH) group in the compound of formula IV into aCH--O--Z--CO₂ H group.

Suitable compounds V include halo-carboxylic acids of formulahal--Z--CO₂ ⁻ Na⁺ wherein Z has its previous significance and hal ishalogen, preferably chlorine. The carboxylic acid salt so obtained maythen be converted into the free acid of formula I or IA.

Alternatively, the compound of formula V may be an unsaturated nitrile,especially acrylonitrile or methacrylonitrile, which is reacted underalkaline conditions with the compound of formula IV to produce thecorresponding cyano derivative, which may be hydrolysed, in conventionalmanner, to give a compound of formula I or IA.

Suitable epoxide starting materials of formula II include:

Epoxyalkanes

1,2-epoxyoctane

1,2-epoxydecane

1,2-epoxydodecane

1,2-epoxytetradecane

1,2-epoxyhexadecane

1,2-epoxyoctadecane

1,2-epoxyeicosane

or mixtures thereof, including commercially available mixturescontaining mixed alkane moieties.

Glycidyl Ethers

n-butylglycidyl ether

n-hexylglycidyl ether

n-octylglycidyl ether

i-octylglycidyl ether

n-decylglycidyl ether

n- or iso dodecyl glycidyl ether

n- or iso tridecyl glycidyl ether

n- or iso tetradecyl glycidyl ether

n- or iso pentadecyl glycidyl ether

n- or iso hexadecyl glycidyl ether

n- or iso octadecyl glycidyl ether

n- or iso eicosyl glycidyl ether

phenyl glycidyl ether

o-cresyl glycidyl ether

m-cresylglycidyl ether

p-cresylglycidyl ether

4-sec butylphenyl glycidyl ether

4-tert butylphenyl glycidyl ether

4-tert octylphenyl glycidyl ether

4-nonylphenyl glycidyl ether

4-dodecylphenyl glycidyl ether

or mixtures thereof such as "Epoxide 8", a commercially availablemixture of C₁₂ and C₁₄ glycidyl ethers supplied by Procter and Gamble.

Glycidyl Thioethers

n-butylglycidyl thioether

tert-butylglycidyl thioether

iso-octylglycidyl thioether

tert-octylglycidyl thioether

iso-nonylglycidyl thioether

n-dodecylglycidyl thioether

iso-dodecylglycidyl thioether

tert-dodecylglycidyl thioether

n-hexadecylglycidyl thioether

tert-hexaglycidyl thioether

phenyl glycidyl thioether

or mixtures there, including commercially available mixtures comprisingmixed alkane moieties.

Suitable alcohol reactants R² --Y--H or R⁴ --Y--H of formula IIIinclude: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol,2-butanol, isobutylalcohol, tert butylalcohol, 1-pentanol,isoamylalcohol, 1-hexanol, 2-hexanol, 1-heptanol, 2-heptanol, 1-octanol,2-octanol, 2-ethylhexanol, 1-nonanol, 2-nonanol, 1-decanol, 2-decanol,1-undecanol, 2-undecanol, phenol, o-cresol, p-cresol, m-cresol,4-sec-butylphenol, 4-tert-butylphenol, 4-tert-octylphenol, 4-nonylphenoland 4-dodecylphenol.

Suitable mercaptans R² --Y--H or R⁴ --Y--H of formula III include:

methane thiol

ethane thiol

1-mercaptopropane

2-mercaptopropane

1-mercaptobutane

2-mercaptobutane

t-butyl mercaptan

1-mercaptohexane

2-mercaptohexane

1-mercaptooctane

t-octylmercaptan

1-mercaptononane

t-nonylmercaptan

1-mercaptodecane

1-mercaptododecane

tert-dodecylmercaptan

thiophenol

thiocresol.

Any amount of the compound of formula I, or mixture thereof, which iseffective as a corrosion inhibitor in the composition according to theinvention can be used, but the amount expediently ranges from 0.0001 to5% by weight, preferably from 0.001 to 3% by weight and especiallypreferred from 0.01 to 2% by weight, based on the total weight of thefunctional fluid base.

The functional fluid base for the compositions of the present inventionis either (a) an aqueous-based system or (b) an oil-based system.

Examples of systems which may provide the base for the compositionsaccording to the present invention include functional fluids such aslubricants e.g. those having a mineral oil, poly-alpha olefin orsynthetic carboxylic acid ester base; hydraulic fluids e.g. those basedon mineral oils, phosphate esters, aqueous polyglycol/polyglycol ethermixtures or glycol systems; oil-in-water or water-in-oil systems;metal-working fluids having, as their base, mineral oil for aqueoussystems; water- or aqueous glycol- or ethylene- or propyleneglycol/methanol based engine coolant systems; transformer- or switchoils; as well as aqueous systems e.g. industrial cooling water; aqueousair-conditioning systems; steam-generating systems; sea-water evaporatorsystems; hydrostatic cookers; and aqueous closed circuit heating orrefrigerant systems.

When a functional fluid system is a synthetic lubricant, examplesthereof include lubricants based on a diester of a dibasic acid and amonohydric alcohol, for instance dioctyl sebacate or dinonyladipate; ona triester of trimethylol-propane and a monobasic acid or mixture ofsuch acids, for instance trimethylol propane tripelargonate,trimethylolpropane tricaprylate or mixtures thereof; on a tetraester ofpentaerythritol and a monobasic acid or mixture of such acids, forinstance pentaerythritol tetracaprylate; or on complex esters derivedfrom monobasic acid, dibasic acids and polyhydric alcohols, for instancea complex ester derived from trimethylol propane, caprylic acid andsebacic acid; or of mixtures thereof.

Other synthetic lubricants are those known to the art-skilled anddescribed e.g. in "Schmiermittel-Taschenbush" (Huethig Verlag,Heidelberg 1974). Especially suitable, apart from the preferred mineraloils are e.g. phosphates, glycols, polyglycols, polyalkylene glycols andpoly-alpha olefins.

In order to improve various applicational properties, a functional fluidcomposition of the invention may also contain other additives such as,for oil-based systems, one or more of antioxidants, metal deactivators,further corrosion or rust inhibitors, viscosity-index improvers,pour-point depressants, dispersants/surfactants or anti-wear additives;and for aqueous-based systems, one or more of antioxidants, othercorrosion- and rust inhibitors, metal deactivators, extreme pressure- oranti-wear buffering agents and anti-foams.

For oil-based systems, examples of other additives are:

Examples of phenolic antioxidants 1. Alkylated Monophenols

2,6-Di-tert.-butylphenol

2-tert.-butyl-4,6-dimethylphenol

2,6-di-tert.-butyl-4-ethylphenol

2,6-di-tert.-butyl-4-n-butylphenol

2,6-di-tert.-butyl-4-i-butylphenol

2,6-di-cyclopentyl-4-methylphenol

2-(β-methylcyclohexyl)-4,6-dimethylphenol

2,6-di-octadecyl-4-methylphenol

2,4,6-tri-cyclohexylphenol

2,6-di-tert.-butyl-4-methoxymethylphenol

2. Alkylated Hydroquinones

2,6-Di-tert.-butyl-4-methoxyphenol

2,5-di-tert.-butyl-hydroquinone

2,5-di-tert.-amyl-hydroquinone

2,6-diphenyl-4-octadecyloxyphenol

3. Hydroxylated Thiodiphenylethers

2,2'-Thio-bis-(6-tert.-butyl-4-methylphenol)

2,2'-thio-bis-(4-octylphenol)

4,4'-thio-bis-(6-tert.-butyl-3-methylphenol)

4,4'-thio-bis-(6-tert.-butyl-2-methylphenol)

4. Alkylidene-Bisphenols

2,2'-Methylene-bis-(6-tert.-butyl-4-methylphenol)

2,2'-methylene-bis-(6-tert.-butyl-4-ethylphenol)

2,2'-methylene-bis-(4-methyl-6-(α-methylcyclohexyl)-phenol)

2,2'-methylene-bis(4-methyl-6-cyclohexylphenol)

2,2'-methylene-bis-(6-nonyl-4-methylphenol)

2,2'-methylene-bis-(4,6-di-tert.-butylphenol)

2,2'-ethylidene-bis-(4,6-di-tert.-butylphenol)

2,2'-ethylidene-bis-(6-tert.-butyl-4-isobutylphenol)

2,2'-methylene-bis-(6-(α-methylbenzyl-4-nonylphenol)

2,2'-methylene-bis-(6-(α,α-dimethylbenzyl)-4-nonylphenol)

4,4'-methylene-bis-(6-tert.-butyl-2-methylphenol)

1,1'-bis-(5-tert.-butyl-4-hydroxy-2-methylphenol)-butane

2,6-di-(3-tert.-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol

1,1,3-tris-(5-tert.-butyl-4-hydroxy-2-methylphenol)-3-n-dodecyl)-mercaptobutane

ethyleneglycol-bis-[3,3-bis-(3'-tert.-butyl-4'-hydroxyphenol)-butyrate]

di-(3-tert.-butyl-4-hydroxy-5-methylphenyl)-dicyclopentadiene

di-[3'-tert.-butyl-2'-hydroxy-5'-methyl-benzyl)-6-tert.-butyl-4-methyl-phenyl]terephthalate

5. Benzyl Compounds

1,3,5-Tri-(3,5-di-tert.-butyl-4-hydroxybenzyl)-2,4,6-trimethyl-benzene

di-(3,5-di-tert.-butyl-4-hydroxybenzyl)-sulphide

bis-(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiol-terephthalate

1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)-isocyanurate

1,3,5-tris-(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)-isocyanurate

3,5-di-tert.-butyl-4-hydroxybenzyl-phosphonic acid-dioctadecylester

3,5-di-tert.-butyl-4-hydroxybenzyl-phosphonic acid-monoethylestercalcium salt

6. Acylaminophenols

4-Hydroxy-lauric acid anilide

4-Hydroxy-stearic acid anilide

2,4-bis-octylmercapto-6-(3,5-di-tert.-butyl-4-hydroxyanilino)-s-triazine

N-(3,5-di-tert.-butyl-4-hydroxyphenyl)-carbamic acid octyl ester

    ______________________________________                                        7. Esters of β-(3,5-Di-tert.-butyl-4-hydroxyphenol)-                     propionic acid with mono- or polyhydric alcohols e.g. with                    ______________________________________                                        methanol     diethyleneglycol                                                 octadecanol  triethyleneglycol                                                1,6-hexanediol                                                                             pentaerythritol                                                  neopentylglycol                                                                            tris-hydroxyethyl-isocyanurate                                   thiodiethyleneglycol                                                                       bis-hydroxyethyl-oxalic acid diamide                             ______________________________________                                    

    ______________________________________                                        8. Esters of β-(5-tert.-butyl-4-hydroxy-3-methylphenyl)-                 propinic acid                                                                 ______________________________________                                        methanol       diethyleneglycol                                               octadecanol    triethyleneglycol                                              1,6-hexanediol pentaerythritol                                                neopentylglycol                                                                              tris-hydroxyethyl-isocyanurate                                 thiodiethyleneglycol                                                                         di-hydroxyethyl-oxalic acid diamide                            ______________________________________                                    

9. Amides of β-(3,5-Di-tert.-butyl-4-hydroxyphenyl)-propionic acid e.g.

N,N'-Di-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyl)-hexamethylene-diamine

N,N'-Di-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyl)-trimethylene-diamine

N,N'-Di-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyl)-hydrazine

Examples of amine antioxidants

N,N'-Di-isopropyl-p-phenylenediamine

N,N'-di-sec.-butyl-p-phenylenediamine

N,N'-bis(1,4-dimethyl-pentyl)-p-phenylenediamine

N,N'-bis(1-ethyl-3-methyl-pentyl)-p-phenylenediamine

N,N'-bis(1-methyl-heptyl)-p-phenylenediamine

N,N'-dicyclohexyl-p-phenylenediamine

N,N'-diphenyl-p-phenylenediamine

N,N'-di-(naphthyl-2)-p-phenylenediamine

N-isopropyl-N'-phenyl-p-phenylenediamine

N-(1,3-dimethyl-butyl)-N'-phenyl-p-phenylenediamine

N-(1-methyl-heptyl)-N'-phenyl-p-phenylenediamine

N-cyclohexyl-N'-phenyl-p-phenylenediamine

4-(p-toluene-sulfonamido)-diphenylamine

N,N'-dimethyl-N,N'-di-sec.-butyl-p-phenylenediamine diphenylamine

4-isopropoxy-diphenylamine

N-phenyl-1-naphthylamine

N-phenyl-2-naphthylamine

octylated diphenylamine

octylated N-phenyl-α-(or)β-naphthylamine

4-n-butylaminophenol

4-butyrylamino-phenol

4-nonanoylamino-phenol

4-dodecanoylamino-phenol

4-isodecanoylamino-phenol

4-octadecanoylamino-phenol

di-(4-methoxy-phenyl)-amine

2,6-di-tert.-butyl-4-dimethylamino-methyl-phenol

2,4'-diamino-diphenylmethane

4,4'-diamino-diphenylmethane

N,N,N'N'-tetramethyl-4,4'-diamino-diphenylmethane

1,2-di-(phenylamino)-ethane

1,2-di-[2-(methyl-phenyl)-amino]-ethane

1,3-di-(phenylamino)-propane

(o-tolyl)-biguanide

di-[4-(1',3'-dimethyl-butyl)-phenyl]amine

Examples of metal passivators are: for copper e.g.

Benzotriazole, tolutriazole, 1,2,4-triazole and derivatives thereof,tetra-hydrobenzotriazole, 2-mercaptobenzothiazole,2,5-dimercapto-thiadiazole, salicylidene-propylenediamine and salts ofsalicylaminoguanidine.

Examples of rust inhibitors are:

(a) Organic acids, their esters, metal salts and anhydrides, e.g.N-oleoyl-sarcosine, sorbitan-mono-oleate, lead-naphthenate,dodecenyl-succinic acid (and its partial esters and amides),4-nonyl-phenoxy-acetic acid.

(b) Nitrogen-containing compounds e.g.

I. Primary, secondary or tertiary aliphatic or cycloaliphatic amines andamine-salts or organic and inorganic acids, e.g. oil-solublealkyl-ammonium carboxylates

II. Heterocyclic compounds e.g. substituted imidazolines and oxazolines

(c) Phosphorus-containing compounds e.g. amino salts of phosphonic acidor acid partial esters, zinc dialkyldithio phosphates

(d) Sulphur-containing compounds e.g.barium-dinonylnaphthalene-n-sulphonates, calcium petroleum sulfonates

Examples of viscosity-index improvers are e.g.

Polymethacrylates, vinylpyrrolidone/methacrylate-copolymers,polybutenes, olefin-copolymers styrene/acrylate-copolymers.

Examples of pour-point depressants are e.g.

Polymethacrylates, or alkylated naphthalene derivatives.

Examples of dispersants/surfactants are e.g.

Polybutenylsuccinic acid-amides or -imides, polybutenylphosphonic acidderivatives, basic magnesium-, calcium- and barium sulphonates and-phenolates.

Examples of anti-wear additives are e.g.

Sulphur- and/or phosphorus- and/or halogen-containing compounds e.g.sulphurised vegetable oils, zinc dialkyldithiophosphates,tritolylphosphate, chlorinated paraffins, alkyl- and aryldisulphides.

For functional fluid bases which are completely aqueous, such as coolingwater systems, air-conditioning systems, steam-generating systems,sea-water evaporator systems, hydrostatic cookers, and closed circuitheating or refrigerant systems, further corrosion inhibitors may be usedsuch as, for example, water soluble zinc salts; phosphates;polyphosphates; phosphonic acids and their salts, for example,hydroxyethyldiphosphonic acid (HEDP), nitrilotris methylene phosphonicacid and methylamino dimethylene phosphonocarboxylic acids and theirsalts, for example, those described in German Offenlegungsschrift No.2632774, hydroxy-phosphonoacetic acid,2-phosphonobutane-1,2,4-tricarboxylic acid and those disclosed in GB No.1572406; nitrates, for example sodium nitrate; nitrites e.g. sodiumnitrite; molybdates e.g. sodium molybdate; tungstates, silicates e.g.sodium silicate; benzotriazole, bis-benzotriazole or copper deactivatingbenzotriazole or tolutriazole derivatives or their Mannich basederivatives; mercaptobenzothiazole; N-acyl sarcosines; N-acyliminodiacetic acids; ethanolamines; fatty amines; and polycarboxylic acids,for example, polymaleic acid and polyacrylic acid, as well as theirrespective alkali metal salts, copolymers of maleic anhydride, e.g.copolymers of maleic anhydride and sulphonates styrene, copolymers oracrylic acid e.g. copolymers or acrylic acid and hydroxyalkylatedacrylic acid, and substituted derivatives of polymaleic and polyacrylicacids and their copolymers. Moreover, in such completely aqueoussystems, the corrosion inhibitor according to the invention may be usedin conjunction with dispersing and/or threshold agents e.g. polymerisedacrylic acid (or its salts), phosphino-polycarboxylic acid (as describedand claimed in British Patent No. 1548235), the cotelomeric compoundsdescribed in European Patent Application No. 0150706, hydrolysedpolyacrylonitrile, polymerised methacrylic acid and its salts,polyacrylamide and co-polymers thereof from acrylic and methacrylicacids, lignin sulphonic acid and its salts, tannin, naphthalenesulphonic acid/formaldehyde condensation products, starch and itsderivatives, cellulose, acrylic acid/lower alkyl hydroxyacrylatecopolymers e.g. those described in U.S. Pat. No. 4,029,577,styrene/maleic anhydride copolymers and sulfonated styrene homopolymerse.g. those described in U.S. Pat. No. 4,374,733 and combinationsthereof. Specific threshold agents, such as for example,2-phosphono-butane-1,2,4-tricarboxylic acid (PBSAM),hydroxyethyldiphosphonic acid (HEDP), hydrolysed polymaleic anhydrideand its salts, alkyl phosphonic acid, hydroxyphosphonoacetic acid,1-aminoalkyl-1,1-diphosphonic acids and their salts, and alkali metalpoly-phosphates, may also be used.

Particularly interesting additive packages are those comprisingcompounds of formula I with one or more of polymaleic acid orpolyacrylic acid or their copolymers, and/or HEDP and/or PBSAM and/ortriazoles e.g. tolutriazole.

Precipitating agents such as alkali metal orthophosphates, carbonates;oxygen scavengers such as alkali metal sulphites and hydrazines;sequestering agents such as nitrilotriacetic acid and its salts;anti-foaming agents such as silicones e.g. polydimethylsiloxanes,distearyl-sebacamides, distearyl adipamide and related products derivedfrom ethylene oxide and/or propylene oxide condensations, in addition tofatty alcohols, such as capryl alcohols and their ethylene oxidecondensates; and biocides e.g. amines, quaternary ammonium compounds,chlorophenols, sulphur-containing compounds such as sulphones, methylenebis thio-cyanates and carbamates, isothiazolones, brominatedpropionamides, triazines, phosphonium compounds, chlorine andchlorine-release agents and organo-metallic compounds such as tributyltin oxide, may be used.

The functional fluid base may be partly aqueous e.g. in aqueousmachining fluid formulation, e.g. a water dilutable cutting or grindingfluid.

The aqueous machining fluid formulations according to the invention maybe e.g. metal working formulations. By "metal working" we mean reaming,broaching, drawing, spinning, cutting, grinding, boring, milling,turning, sawing, non-cutting shaping, rolling or quenching. Examples ofwater-dilutable cutting or grinding fluids into which the corrosionsinhibiting compound may be incorporated include:

(a) Aqueous concentrates of one or more corrosion inhibitors, andoptionally one or more anti-water additives which are usually employedas grinding fluids;

(b) Polyglycols containing biocides, corrosion inhibitors and anti-wearadditives for cutting operations or grinding;

(c) Semi-synthetic cutting fluids similar to (b) but containing inaddition 10 to 25% oil with sufficient emulsifier to render the waterdiluted product translucent;

(d) An emulsifiable mineral oil concentrate containing, for example,emulsifiers, corrosion inhibitors, extreme pressure/anti-wear additives,biocides, antifoaming agents, coupling agents etc; they are generallydiluted with water to a white opaque emulsion;

(e) A product similar to (d) containing less oil and more emulsifierwhich on dilution gives a translucent emulsion for cutting or grindingoperations.

For those partly-aqueous systems in which the functional fluid is anaqueous machining fluid formulation the inhibitor of formula I may beused singly, or in admixture with other additives e.g. known furthercorrosion inhibitors or extreme-pressure additives.

Examples of other corrosion inhibitors which may be used in these partlyaqueous systems, in addition to the compound of formula I used accordingto the invention, include the following groups:

(a) Organic acids, their esters or ammonium, amine, alkanolamine andmetal salts, for example, benzoic acid, p-tert.-butyl benzoic acid,disodium sebacate, triethanolamine laurate, iso-nonanoic acid,triethanolamine salt of p-toluene sulphonamide caproic acid,triethanolamine salt of benzene sulphonamide caproic acid,triethanolamine salts of 5-ketocarboxylic acid derivatives as describedin European Patent No. 41927, sodium N-lauroyl sarcosinate or nonylphenoxy acetic acid;

(b) Nitrogen containing materials such as the following types: fattyacid alkanolamides; imidazolines, for example,1-hydroxyethyl-2-oleyl-imidazolines; oxazolines; triazoles for example,benzotriazoles; or their Mannich base derivatives; triethanolamines;fatty amines, inorganic salts, for example, sodium nitrate; and thecarboxy-triazine compounds described in European Patent No. 46139;

(c) Phosphorus containing materials such as the following types: aminephosphates, phosphonic acids or inorganic salts, for example, sodiumdihydrogen phosphate or zinc phosphate;

(d) Sulphur containing compounds such as the following types: sodium,calcium or barium petroleum sulphonates, or heterocyclics, for example,sodium mercaptobenzothiazole. Nitrogen containing materials,particularly triethanolamine, are preferred.

The following Examples further illustrate the present invention.Percentages and parts are by weight unless otherwise stated.

EXAMPLE 1 2-Carboxymethyl-1-isooctyl-3-methyl glycerol

Sodium metal (2.3 g; 0.1 mole) is dissolved in methanol (160 g; 5moles). The solution is heated to reflux and treated dropwise over 2hours with isooctyl glycidyl ether (186 g; 1 mole). After completeaddition, the reaction mixture is maintained under reflux conditions fora further 6 hours. After cooling to ambient temperature, the reactionmixture is treated with acetic acid (5.8 g; 0.1 mole) and then theexcess solvent is removed under vacuum. The oily residue is treated withwater (250 ml) and then extracted with ether (250 ml). The ether extractis dried over MgSO₄, filtered and evaporated. The residue is distilledunder vacuum to yield 1-isooctyl-3-methyl glycerol, as a colourless oil,bp 75°-80° C./0.07 mbar, yield 145.6 g (67%).

109 g (0.5 mole) of 1-isooctyl-3-methyl glycerol obtained as above arestirred vigorously with sodium chloroacetate (58.3 g; 0.5 mole) at40°-50° C. and treated portionwise over 3 hours with powdered sodiumhydroxide (20 g; 0.5 mole). After complete addition, the reactionmixture is stirred for a further 6 hours at 40°-50° C. The reactionmixture is then treated with 10% H₂ SO₄ to adjust the pH to 2 and, afterheating to 80° C., two layers are formed. The upper organic layer isseparated, treated with water (200 ml) and extracted with ether. Theether extract is washed with water then dried over MgSO₄. The filteredextract is evaporated and the residue is distilled under vacuum to yield2-carboxymethyl-1-isooctyl-3-methyl glycerol, as a colourless oil, bp.136°-140° C./0.07 mbar, yield=93.8 g (68%).

Analysis: Found: C 61.23%; H 10.55%. C₁₄ H₂₈ O₅ requires: C 60.84%; H10.21%.

EXAMPLE 2 2-(1-(Methoxymethylundecyloxy)acetic acid

1,2-Epoxydodecane is reacted with sodium in methanol as in Example 1 toyield 1-methoxy-2-dodecanol as a colourless oil, bp 97° C./0.07 mbar,yield 88%.

108 g (0.5 mole) 1-methoxy-2-dodecanol are reacted with sodiumchloroacetate (58.3 g; 0.5 mole) and powdered sodium hydroxide (20 g;0.5 mole) as in Example 1 to yield 2-(1-Methoxymethylundecyloxy)aceticacid as a colourless oil, bp. 162° C./0.26 mbar, yield 59.0 g (43%).

Analysis: Found: C 66.05%; H 11.42%. C₁₅ H₃₀ O₄ requires: C 65.65%; H11.02%.

EXAMPLE 3 2-Carboxymethyl-1-methyl-3-tertnonylthio glycerol

tert-Nonylthioglycidyl ether is reacted with sodium in methanol as inExample 1 to yield 1-methoxy-3-tert-nonylthioglycerol as a colourlessoil, bp 106°-110° C./0.26 mbar, yield 81%.

74.4 g (0.3 mole) tertnonylthioglycerol are reacted with sodiumchloroacetate (46.4 g; 0.3 mole) and powdered sodium hydroxide as inExample 1 to yield 2-carboxymethyl-1-methyl-3-tert-nonylthioglycerol asa colourless oil, bp 195° C./0.07 mbar, yield 36%. Satisfactory infraredand nmr spectra are obtained for the title product.

EXAMPLES 4 TO 19

Using methods analogous to that set out in Example 1, compounds havingthe formula: ##STR9## are prepared.

    ______________________________________                                        Example                                                                              R.sup.1   R.sup.2 X    Y   n   bp                                      ______________________________________                                        4      C.sub.8 H.sub.17                                                                        C.sub.8 H.sub.17                                                                      O    O   1   184° C./0.07 mbar                5      C.sub.10 H.sub.21                                                                       C.sub.10 H.sub.21                                                                     O    O   1   215° C./0.07 mbar                6      C.sub.12 H.sub.25                                                                       C.sub.12 H.sub.25                                                                     O    O   1   undistilled oil                         7      C.sub.12 H.sub.25 /                                                                     CH.sub.3                                                                              O    O   1   195-205° C./0.26                        C.sub.14 H.sub.29              mbar                                           mixture                                                                8      C.sub.12 H.sub.25                                                                       C.sub.4 H.sub.9                                                                       O    O   1   207° C./0.13 mbar                9      .sup.t C.sub.12 H.sub.25                                                                CH.sub.3                                                                              S    O   1   210° C./0.10 mbar                10     C.sub.10 H.sub.21                                                                       CH.sub.3                                                                              CH.sub.2                                                                           O   1   174° C./0.07 mbar                11     C.sub.6 H.sub.5                                                                         CH.sub.3                                                                              O    O   1   185° C./0.40 mbar                12     C.sub.9 H.sub.19                                                                        CH.sub.3                                                                              O    O   1   212° C./0.07 mbar                       (60% meta                                                                     40% para)-                                                                    phenyl                                                                 13     C.sub.12 H.sub.25 /                                                                     CH.sub.3                                                                              O    O   1   200-216° C./0.4                         C.sub.13 H.sub.27              mbar                                    14     C.sub.6 H.sub.13                                                                        C.sub.4 H.sub.9                                                                       O    O   1   154° C./0.08 mbar                15     C.sub.4 H.sub.9                                                                         C.sub.4 H.sub.9                                                                       O    O   1   142° C./0.08 mbar                16     .sup.t C.sub.4 H.sub.9                                                                  .sup.n C.sub.4 H.sub.9                                                                S    O   1   146° C./0.04 mbar                17     C.sub.12 H.sub.25                                                                       CH.sub.3                                                                              O    O   1   180° C./0.02 mbar                18     C.sub.13 H.sub.27                                                                       CH.sub.3                                                                              O    O   1   180° C./0.02 mbar                19     C.sub.14 H.sub.29                                                                       CH.sub.3                                                                              O    O   1   190° C./0.03                     ______________________________________                                                                              mbar                                

EXAMPLES 20 TO 33 Corrosion Inhibition in oils

Several of the products used according to the present invention aretested as rust inhibitors in a turbine grade oil of viscosity 26.2 mm²/s at 40° C., 4.8 mm² /s at 100° C. and sulphur content of 0.54%, usingthe ASTM D665B method. The test results are expressed in the followingmanner

Rating

0--No rust or traces of rust on test spindle

1--Rusting confined to not more than 6 spots, each of which is 1 mm orless in diameter

2--Rusting in excess of the above but confined to less than 5% of thesurface of the spindle

3--Rusting covering more than 5% of the surface of the spindle

    ______________________________________                                               Corrosion Inhibitor       ASTM D665B                                   Example                                                                              Product of Example                                                                          Concentration                                                                             rating                                       ______________________________________                                        --     none (control)                                                                              --          3                                            20     1             0.05%       0                                            21     2             0.05%       0                                            22     3             0.05%       0                                            23     4             0.05%       0                                            24     5             0.05%       0                                            25     6             0.05%       2                                            26     7             0.05%       0                                            27     8             0.05%       0                                            28     9             0.05%       1                                            29     10            0.05%       0                                            30     12            0.05%       0                                            31     13            0.05%       0                                            32     17            0.05%       0                                            33     19            0.05%       0                                            ______________________________________                                    

EXAMPLES 34 TO 42 Corrosion Inhibitor in metal working fluid

Several of the products used according to the present invention aretested as rust inhibitors in aqueous cutting fluid using the IP287chip/filter paper method. One percent solutions of the products areprepared in DIN 51360 water in the form of their triethanolamine saltsand the test results are expressed in the following manner.

Rating

0--No corrosion

1--maximum of 3 corrosion spots each of which is less than 1 mm indiameter

2--Not more than 1% of the surface stained

3--Above 1% but below 5% of the surface stained

4--Above 5% of the surface stained

    ______________________________________                                                 Corrosion Inhibitor                                                  Example  Product of Example                                                                            pH    IP 287 Rating                                  ______________________________________                                        --       none (control)  9.0   4                                              34       1               9.0   0                                              35       2               9.0   0                                              36       4               9.0   0                                              37       7               9.0   0                                              38       10              9.0   0                                              39       11              9.0   2                                              40       14              9.0   0                                              41       15              9.0   0                                              42       16              9.0   0                                              ______________________________________                                    

EXAMPLES 43 TO 48 Corrosion Inhibition in Cooling Water

Several of the products used according to the present invention aretested as corrosion inhibitors by a rotating coupon test in thefollowing corrosive water:

    ______________________________________                                               pH       7.0                                                                  pA       0                                                                    TA       20                                                                   TH       75                                                                   Ca.sup.2+ (ppm)                                                                        50                                                                   Mg.sup.2+ (ppm)                                                                        25                                                                   Cl.sup.- (ppm)                                                                         20                                                                   SO.sub.4.sup.2- (ppm)                                                                  20                                                            ______________________________________                                    

In a 1 liter reservoir of the test water, two pre-cleaned andpre-weighed mild steel coupons are rotated at a coupon velocity of 61cms per second. The test is conducted over 48 hours in oxygenated waterat 40° C. using 20 ppm in examples 43 to 45 and 15 ppm in examples 46 to48 of the appropriate concentration of corrosion inhibitor.

The coupons are removed, scrubbed, immersed for one minute inhydrochloric acid inhibited with 1% by weight of hexamine and thenrinsed, dried and reweighed. A certain loss in weight will haveoccurred. A blank test i.e. immersion of mild steel specimen in the testwater in the absence of any potential corrosion inhibitor, is carriedout with each series of tests. The corrosion rates are calculated inmilligrams of weight loss/sq. decimeter/day (m.d.d.). The resultsobtained in a series of tests are set out in the following Table.

    ______________________________________                                               Corrosion Inhibitor                                                                         Concentration                                                                             Corrosion rate                               Example                                                                              Product of Example                                                                          (ppm)       (m.d.d.)                                     ______________________________________                                        --     Blank         --          275.8                                        43      7            20          7.0                                          44      2            20          12.1                                         45     10            20          7.7                                          46     17            15          15.0                                         47     18            15          7.0                                          48     19            15          7.0                                          ______________________________________                                    

What is claimed is:
 1. A method of protecting a metal surface againstcorrosion comprising contacting the metal surface with a functionalfluid containing an effective corrosion inhibiting amount of a compoundof the formula I: ##STR10## as well as salts or esters thereof, whereinR¹ is C₄ -C₂₀ linear or branched alkyl, phenyl or C₇ -C₂₀ alkylphenyl;R²is C₁ -C₁₂ linear or branched alkyl, phenyl or C₇ -C₂₀ alkylphenyl, orarylalkyl containing 7-20 carbon atoms; X is CH₂, O or S; Y is O or S;and Z is --(CH₂)_(n) -- in which n is 1, 2, 3, 4 or 5, or Z is --CH₂--CH(CH₃)--.
 2. Method according to claim 1 whereinR¹ is C₉ -C₁₆ linearor branched alkyl, phenyl or C₇ -C₁₅ alkylphenyl; R² is C₁ -C₃ linear orbranched alkyl; X is CH₂, O or S; Y is O; and Z is --(CH₂)-- or --(CH₂)₂--.
 3. Method according to claim 1 wherein the metal surface is aferrous metal surface.
 4. Method according to claim 1 wherein the amountof the compound of formula I ranges from 0.0001 to 5% by weight, basedon the total weight of the functional fluid.
 5. Method according toclaim 1 wherein the functional fluid is oil-based.
 6. Method accordingto claim 5 wherein the fluid also contains one or more antioxidants,metal deactivators, further corrosion or rust inhibitors,viscosity-index improvers, pour-point depressants,dispersants/surfactants or anti-wear additives.
 7. Method according toclaim 1 wherein the functional fluid is completely aqueous.
 8. Methodaccording to claim 7 wherein the fluid also contains one or more furthercorrosion inhibitors, dispersing and/or threshold agents, precipitatingagents, oxygen scavengers, sequestering agents, antifoaming agents orbiocides.
 9. Method according to claim 1 wherein the functional fluid ispartly aqueous.
 10. Method according to claim 9 wherein the fluid alsocontains one or more further corrosion inhibitors or extreme-pressureadditives.